PRESSURE-TIGHT SLUICE

Abstract: A pressure-tight sluice for feeding powder material e.g. from a silo to a pressure container is able to establish a substantial pressure difference with a minimum consumption of air. This is achieved by a novel sluice housing (1, 3) with a superelliptical torus shape and with adapted inlet (5) and outlet (7) which provide a favourable powder flow and efficiency of utilization. Further, the sluice has an effective and self-adjusting compressed-air controlled sealing system which enables substantially larger pressure difference as a consequence of efficient sealing (17) between rotor and housing (1, 3). By means of a pressure equalization line (45) between the return side and powder side of the sluice, a further saving of air is achieved.

Description: PRESSURE-TIGHT SLUICE. The invention relates to sluices for feeding or dosing powder material e.g. from a silo to a pressure container or to a pneumatic transport installation. The purpose is to increase filling degree and rpm by means of a novel design of housing, inlet and outlet, to increase the pressure difference and eliminate air leakage between the housing and the rotor by means of a new sealing arrangement, and to reduce the loss between output and input air amount by establishing pressure equalization between return and filling sides in the rotor . A dominating number of previously known such sluices have a cylindrical housing and a rotor with opposite and downward directed inlet and outlet, where the intersection with the cylinder surface is shaped either circularly or rectangularly. There is also known sluices having ball-shaped housings with a circular or square inlet and outlet. Due to matters related to machining and risk of metallic engagement between rotor and housing during operation, ordinary sluices have a clearance of about 0,1 mm which gives a large leakage. In order to improve the sealing between the rotor and the housing, there exist re-adjustable sealing plates made of plastic. There is also known self-adjusting gaskets lying in channel-shaped grooves in the outer edge of the rotor blades, against the housing wall, and where a radially displaceable gasket pushes toward the housing wall by means of a springy support on the underside of the gasket. In this connection it is referred to Norwegian patent no. 141.313. Regarding the difference in the amount of air between feedout empty rotor and air in the powder which is fed in, this is a loss which is accepted in previously known sluices. In accordance with the invention, the above mentioned deficiencies are remedied by means of a novel geometrical design of the housing and of the inlet and outlet, providing an improved powder flow through the nozzle. Further, the leakage air between rotor and sluice wall is substantially eliminated by means of a new compressed air controlled gasket pushing toward the housing wall where sealing is required, and with relaxation of pressure for the inlet and outlet zones to avoid bulging of the gasket in the openings. Also the air loss between feedout- and feedin-amount of air for the rotor is reduced in this case by means of an added transfer line between the two sluice sides. In order to achieve these particular advantages, the housing has been provided with a shape substantially like a torus having a superelliptical cross section, i.e. the housing inner space appears by rotating a superellipse with its area and its major axis parallel to and outside the rotation axis. A superellipse is here defined as the curve intermediate between an ellipse and a circumscribed rectangle. For the inlet and the outlet there has also been chosen a superelliptical shape in the transition zone to the housing cavity, whereby the opening zones will take a relatively smaller part of the circumference than when using circular and rectangular inlets. Further, the outer and critical corners against the end gables in ordinary sluices are avoided regarding filling and emptying. For disassembling purposes the inner cavity of the housing is split in the middle to enable removal of the rotor. In order to maintain the advan¬ tage of non-split inlet and outlet flanges, the end pieces are located in the largest part of the housing, while the smallest part is led cylindrically into the largest one having a common gable flange. In order to obtain a tight seal between rotor and housing, and at the same time a gasket which does not bulge out when it passes the inlet and the outlet, the gasket has an adjustable air pressure as a pressure for sealing instead of the steadily springy support which is previously known. The gasket may consist of a wear-resisting outer band glued to an underlying flexible hose, or the hose and the wear-resisting outer band may be integrated and possibly manufactured by extrusion. The compressed air which expands the hose, seals radially against the housing and at the same time tightens sideways in the lamella groove. When the inlet and outlet openings are passed, pressure is relaxed and gasket bulging is avoided. Air all the way to the gasket as well as return air pass through a separate hole system for each lamella, along through the axis to a distribution flange on the forward side of the rotor. The length of the gasket is equal to the length of the groove in the lamella against the housing, and continues a little into the lamella and the rotor from both sides for fixing the gasket with a possibility of movement in the lengthwise direction. In order to reduce the amount of air between feedout air and air content in powder fed in, the rotor must have a suffi- cient number of chambers and a sufficiently large sealing part of the circumference for this to take place. In the preferred embodiment of the sluice according to the invention, a line has been added with a return valve which will transfer air from the return side to the feeding side until pressures are equalized. Particularly in sluices operating with a large pressure difference between inlet and outlet, this feature may provide a substantial saving of air. The sluice in accordance with the invention is shown in the appended drawings, as follows: Fig. 1 A-A: The sluice in a front view and in mid-section B-B: The sluice in a view from above and in mid-section Fig. 2 E : A section through a preferred gasket F : A section through a pressurized gasket, mounted in a lamella C-C and D-D: Air distribution to and from gasket Fig. 3 : Sluice having a line connection and a return valve. Sluice housing parts 1 and 3 in fig. 1 form an inside superelliptical torus-shaped cavity which is split along the middle inside, housing part 3 being led into part 1 with a common flange 5. Inlet 7 and outlet 9 are placed in part 1 with circular flanges and with approximately superelliptical transitions 11 toward the sluice cavity. The rotor is shown having 8 lamellas 13 which in this case are glued to the axis 15 and supported by tight ball bearings 17 and 19. In the rear side of the sluice there is an axle outlet with a coup¬ ling 21 and a wedge connection 23 to a stepless variator drive with a gear 25. In the lamella 13 there is a gasket groove 27 which is shown in fig. 2 F with a gasket 31 in place. The gasket 31 seals against housing parts 1 and 3, and both groove and gasket are extended in both ends with pockets 29. The gasket 31 is in the embodiment shown glued together from a hard, wear-resisting band 35 and a soft, elastic rubber hose . 37 which on receiving an excess pressure will expand and push the wearing surface sealingly toward the housing wall and itself tighten against the groove in the lamella. Fig. 2 shows in section C-C how the gasket air, which should have a pressure 1-2 Bar in excess of the maximum sluice pressure, is conducted to the gasket from a distribution flange 39 and a milled groove 41. Correspondingly, the air is evacuated through the distribution flange 39 when the lamellae pass the inlet and outlet openings 7 and 9, through a milled hole groove 43. In fig. 3 the sluice is seen in a front view with a line connection 45 and return valve 47. When the lamellae pass the mid-position, air having outlet pressure will flow through line 45 until pressures in both sides are equalized. The amount of air flowing from one side to the other, will in sluices operating with a large pressure difference mean a large relative saving of air when the sluice is pressure-tight in other respects.

Claims: P A T E N T C L A I M S 1.' Pressure-tight sluice for feeding powder material, e.g. from a silo to a pressure container or to a pneumatic trans- port installation, said sluice comprising a housing (1,3) having an inlet (7) and an outlet (9) located in opposition to each other, and having a rotor with an axle (15) and radially extended lamellae (13) mounted thereon, said lamellae (13) sliding with their outer edges against the inside housing wall in a sealing engagement during rotation, thereby providing a number of chambers between said lamellae (13) , said rotor axle (15) and said inside wall, the outer edges of said lamellae (13) being equipped with a self-adjusting gasket (31) for sealing against the inside housing wall, c h a r a c t e r i z e d in that said inside housing wall is shaped substantially like a torus with a superelliptical cross section, each lamella (13) having a corresponding super¬ elliptical shape for achieving complementary sealing thereto, and that each respective lamella gasket (31) comprises an under¬ lying, rapidly pressurizable and evacuatable air hose (37) with an elastic wall for rapid control of the gasket (31) pressure against the housing wall. 2. Sluice in accordance with claim 1, c h a r a c t e r i z e d in that said lamella gasket (31) lies in a peripheral groove (27) on each lamella (13) , and that one end (29) of said air hose (37) in each gasket has a hole connection through said axle (15) to a compressed air distributor (39) which thus cooperates with a ring of holes in one end of said axle (15) for filling and emptying said air hoses (37) in correspondence with the instantaneous angular position of said rotor. 3. Sluice in accordance with claim 1 or claim 2, c h a r a c t e r i z e d in that said air hose is inte¬ grated with said gasket (31) in such a manner that said gasket (31) is constituted by a possibly extruded air hose with a solid thickening as a wearing part on the top side thereof. 4. Sluice in accordance with claim 1 or claim 2, c h a r a c t e r i z e d in that each gasket (31) is constituted by an air hose (37) and an overlying part (35) of wear-resisting material glued thereto. 5. Sluice in accordance with one of the preceding claims, c h a r a c t e r i z e d in that the housing inlet (7) and outlet (9) have a superelliptical shape in the the inter¬ section with the inside housing wall. 6. Sluice in accordance with one of the preceding claims, c h a r a c t e r i z e d in that said housing (1,3) is internally split in the middle, whereby a first housing part (1) comprises said inlet (7) and outlet (9) including flanges, and a second housing part (3) is adapted to be slid into said first housing part (1) and fixed thereto by means of a common end flange (5) . 7. Sluice in accordance with one of the preceding claims, c h a r a c t e r i z e d by a line connection (45) for pressure equalization, arranged between the return side of said sluice and the feeding side thereof, respectively defined as those two sections of the housing inner space which is without powder and containing powder during operation, as well as a return valve (47) mounted in said line connection (45) , whereby air can be transferred from said return side to said feeding side.

Inventors: HIORTH HANS, HIORTH, HANS
Applicants: HIORTH HANS, HIORTH, HANS
Application year: 1994
Main classification: B65G53
IPC codes: B65G53